大额存单是一种具有较高利率的银行储蓄产品，通常需要存入一笔较大的金额。与普通存款不同，大额存单并没有凭证式的形式。这可能在一定程度上给人一种不安全或者不便利的感觉，但实际上，没有凭证式的设计是有其合理性的。

首先，大额存单的最大特点是其固定期限和固定利率。一旦购买了大额存单，存款人需要将资金锁定在一段较长的时间内，无法提前支取或者部分支取。这意味着存款人享受着更高的利率回报，而银行也能更好地管理资金流动性。在这种情况下，大额存单本身就是一份有效的凭证，表明存款人与银行之间的约定和协议。

其次，大额存单的安全性也不会因为缺少凭证式而受到影响。银行作为专业金融机构，对于大额存单的发行和管理都有严格的规章制度。所有的交易和记录都被银行系统完整地记录，以确保账户的安全和透明度。此外，大额存单通常都有相应的保险机制来保障存款人的权益。

最后，大额存单之所以没有凭证式，也是为了提高存款人的灵活性和便利性。如果大额存单有凭证式，那么存款人在需要资金的时候就需要较为繁琐的手续，例如填写申请表、签署文件等。而没有凭证式的设计，则可以使存款人更加灵活地支配自己的资金，无需进行多余的操作。

总结来说，大额存单之所以没有凭证式，是根据其特点和目的而设计的。存款人通过购买大额存单可以享受更高的利率回报，而银行则能够更好地管理资金流动性。此外，大额存单的安全性也是得到保障的。因此，尽管没有凭证式，大额存单仍然是一种可信赖和便利的投资选择。

大额存单（Large Time Deposit）is a type of bank savings product with a higher interest rate, which usually requires a large amount of money to be deposited. Unlike ordinary deposits, large time deposits do not have a voucher-style form. This may give people a sense of insecurity or inconvenience, but in fact, the lack of a voucher-style design is reasonable.

Firstly, the biggest characteristic of large time deposits is their fixed term and fixed interest rate. Once a large time deposit is purchased, the depositor needs to lock the funds for a relatively long period of time and cannot withdraw or partially withdraw them in advance. This means that depositors enjoy a higher rate of return, and banks can better manage fund liquidity. In this case, the large time deposit itself is an effective voucher, indicating the agreement and arrangement between the depositor and the bank.

Secondly, the lack of a voucher-style does not affect the security of large time deposits. As professional financial institutions, banks have strict regulations on the issuance and management of large time deposits. All transactions and records are recorded in the bank's system to ensure the security and transparency of the account. Additionally, large time deposits usually have corresponding insurance mechanisms to protect the rights and interests of depositors.

Finally, the absence of a voucher-style for large time deposits is also to enhance the flexibility and convenience for depositors. If large time deposits have a voucher-style, depositors would need to go through cumbersome procedures such as filling out application forms and signing documents when they need funds. The lack of a voucher-style design allows depositors to have more flexible control over their funds without unnecessary operations.

In conclusion, the lack of a voucher-style for large time deposits is designed based on its characteristics and purposes. Depositors can enjoy a higher rate of return by purchasing large time deposits, and banks can better manage fund liquidity. Additionally, the security of large time deposits is guaranteed. Therefore, despite the lack of a voucher-style, large time deposits are still a trustworthy and convenient investment choice.